Rotary-percussion drill apparatus



Get. 21, 1969 F. w. BECKER ROTARY-PERCUSSION DRILL APPARATUS Filed June5, 1968 INVENTOR. flaw v1! flee/445R United States Patent US. Cl. 1752157 Claims ABSTRACT OF THE DISCLOSURE An apparatus for sinking a boreholeby rotary-percussive means and collecting the earth fragments. Theapparatus comprises a drill pipe having a bit end, a drive end and aninterior tube in the drill pipe which defines an annular space betweenthe drill pipe and the interior tube. Means for maintaining the interiortube in coaxial relation while permitting axial movement includesradially aligned spacer blocks and a spout stock secured to the drillend of the drill pipe, A bit secured to the bit end of the drill pipehas an annular portion adapted to seat the interior tube; an openingthrough the annular portion and passages communicating the opening withthe annular space defined by the interior tube and drill pipe.

This invention relates to the rotary-percussive piercing of earthformations, and has to do particularly with an apparatus adapted to sinka bore hole through both overburden and bedrock, while permittingimmediate collection of fragments of the earth formation penetrated asthe fragments are loosened, to enable continuous monitoring and exactlogging of the bore hole.

Conventional rotary-percussive drilling apparatus usually includes ahollow drill-pipe, a rotary-percussive drill mechanism from whichextends a coupling through which rotation, percussion and pressurizedfluid are transmitted to the drill-pipe, and a drill bit at the bottomend of the drill-pipe. The drill bit is of a size whereby it cuts a borehole appreciably larger than the drill-pipe, and the annular spacebetween the drill-pipe and the walls of the bore hole provides a passagefor the return of the pressurized fluid, usually air, which is forceddown the inside of the drill-pipe. As the drill bit chips away the earthformation, the pressurized air or other fluid takes up the chips andcuttings and carries them up between the drillpipe and the bore hole tothe surface of the earth where they can be either collected for testingor discarded.

One disadvantage of the conventional apparatus just described is that,while it is capable of satisfactory drilling in bed rock where the wallsof the bore hole are solid, it does not work well in overburden, wherethe loose and unconsolidated walls of the bore hole have a tendency tocollapse and block up the return passage, so that the cuttings cannot becarried up to the surface. Even when the walls of the bore hole inoverburden are sul'ficiently consolidated to resist collapse, there is arisk that the returning chips will become contaminated with materialfrom the walls of the bore hole during the upward return passage,thereby giving test readings which do not accurately represent the trueprofile of the earth formation being drilled. The same problem can arisein bedrock, especially when some of the pierced strata are of weakermaterial, such as sandstones or weak clays.

It is therefore an object of this invention to provide arotary-percussive drill apparatus wherein the aforementioneddisadvantages are overcome.

Essentially, this object is achieved by providing apparatus permitting areverse-flow for the pressurized fluid employed. Instead of the fluidreturn taking place between the drill-pipe and the bore hole walls,where col- "ice lapse or contamination can take place, the return flowof fluid passes upwardly through the centre of a second coaxial tubewithin the drill-pipe, the down flow of fluid passing down the annularspace between the interior tube and the drill-pipe. In order to provideapparatus of this nature, two problems require solution. The first ofthese relates to the way in which the interior tube should be supportedinside the exterior drill-pipe, and the second has to do with the waypressurized fluid is fed to the annular space between the interior tubeand the drillpipe and the way in which the upflowing mixture of fluidand rock chips is exhausted to the outside.

Accordingly, this invention provides, in combination, a drill-pipehaving a bit end and a drive end, a bit carried by said bit end, aninterior tube positioned within said drill-pipe to define an annularspace between the drillpipe and the interior tube, means for maintainingthe interior tube in a substantially coaxial relation to said drillpipewhile permitting axial movement of the interior tube relative to saiddrill-pipe, said bit having an annular portion against which the lowerend of the interior tube is adapted to seat, said bit having an openingextending through the bit within said annular portion, said bit havingpassage means communicating said annular space with said opening.

One embodiment of this invention is shown in the accompanying drawings,in which like numerals denote like parts throughout the several views,and in which:

FIGURE 1 is an axial sectional view, broken at two axial locations, of adrilling apparatus; and

FIGURE 2 is a cross-sectional view taken at the line 22 in FIGURE 1.

A drilling apparatus, generally shown at 10 in FIG- URE 1, consistsessentially of a drill-pipe 12, an interior tube 14, a spout stock 16connected to the drive end of the drill-pipe 12, and a bit 18 connectedto the bit end of the drill-pipe 12.

The drill-pipe 12 is preferably a high carbon steel pipe of a typereadily available on the open market. By way of illustration only, thedrill-pipe 12 may have an CD. of 4% inches and an ID. of 3% inches, andeach section of the drill-pipe 12 may be between 9 and 10 feet long. Theends of each section of drill-pipe 12 are internally threaded, thethread shown in the drawings being the box thread type. In FIGURE 1,there is shown an upper drill-pipe section 20 and a lower drill-pipesection 21. The two sections 20 and 21 are linked together by means of aconnector pin 22, which is again a standard item available on the openmarket. The connector pin 22 is made of a material which is weaker thanthe material of the drill-pipe 12, and this ensures that, underexcessive loads, the connector pin 22 will break before the drill-pipe12. As shown, the connector pin 22 has two male threaded ends 23 adaptedto engage the ends of the sections 20 and 21.

The bit 18 has a male threaded portion 24 for threaded engagement withthe lower end of the section 21 of drillpipe 12. The exact tooth shape,etc., of the bit 18 does not form a part of this invention and will notbe described in detail in the specification. It is essential to thisinvention, however, that the bit 18 employed meet the followingrequirements. Firstly, it should be suitable for use withrotary-percussion drilling apparatus, in which the vibrations orpercussions transmitted to the bit cause the bit teeth to chip the rockbeing traversed. Secondly, the bit must have an opening 26 extendingthrough the bit along the axis of the drill-pipe 12. Thirdly, theopening 26 must have an annular ledge 28 upon which an interior tube 14,later to be described in greater detail, can seat. The fourthrequirement relates to the fact that the interior tube 14 is positionedwithin the drill-pipe 12 to define an annular space 32 between thedrill-pipe 12 and the interior tube 14, the fourth requirement beingthat the bit 18 have passage means communicating the annular space 32with the opening 26 below the annular ledge 28. In FIGURE 1 passages 34are shown extending from the opening 26 to a reduced annular space 36between the interior tube 14 and the male threaded portion 24, thereduced annular space 36 being in communication with the annular space32. It is also preferable that the bit 18 have a slight downward flareas shown, but this is not considered essential.

It will be noted that the bit 18 has a bore 40 of a larger diameter thanthe opening 26, and that the difference in these diameters is whatdefines the ledge 28. Although the interior tube 14 is shown to fitsnugly within the bore 40, it is essential that the fit between thesetwo be loose enough to permit unrestrained axial motion of the interiortube 14 with respect to the bit 18.

The interior tube 14 is a relatively thin-walled mechanical tubing,which is preferably a standard steel pipe. By way of illustration onlythe interior tube 14 may have an CD. of 2% inches and an ID. of 2inches. This invention provides that the interior tube 14 be completlyfree of any rigid attachment to the drill-pipe 12, and that moreover itbe free to move axially with respect to the drill-pipe 12. In FIGURE 1,the connection between two adjacent sections of interior tube 14 is seento involve the provision, at one end of each section of interior tube14, of a cylindrical member 42 which is welded or otherwise secured tothe end of the section of interior tube 14. The cylindrical member 42has an interior ridge 43 which abuts against the end of the section towhich the member 42 is secured, and also has an internal gallery 44which receives a circular sealing member such as an O- ring. The end 46of the other section of interior tube 14 fits snugly within thecylindrical member 42 as shown.

In order to maintain the coaxial relation between the interior tube 14and the drill-pipe 12 when a large number of sections of drill-pipe 12is in use, each section of interior tube 14 is provided with threeaxially aligned but circumferentialy distributed spacer blocks 48 which.are welded to the outside wall of the interior tube 14. It ispreferably, of course, that the spacer blocks be equally spaced aroundthe outside of the interior tube 14. The radial dimension of the spacerblocks is slightly less than the radial dimension of the annular space32, thereby permitting a small amount of lateral play as between theinterior tube 14 and the drill-pipe 12. More importantly, thisarrangement permits unimpeded axial movement of the interior tube 14with respect to the drillpipe 12.

At the upper end of the section 20 of the drill-pipe 12 is attached afurther connector pin 50 identical in all respects to the connector pin22. The connector pin 50 joins the section 20 of the drill-pipe 12 tothe spout stock 16, the latter having at its lower end a female threadedportion 51 for engagement with the connector pin 50. The spout stock 16has an internal, coaxial, downward-opening bore 52 in which the upperend of the uppermost section of the interior tube 14 is received. Thedownward-opening bore 52 has an interior gallery 53 adapted to carry acircular sealing ring, such as an O- ring. The sealing rings in thegalleries 44 and 53 prevent the passage of fluid, for example air,between the annular space 32 and the inside of the interior tube 14. Thedown ward-opening bore 52 has a step 55 which limits the axial movementof the interior tube 14 in the upward direction. The bore 52 has alateral extension 56 which opens through the side of the spout stock 16,thereby providing communication between the inside of the interior tube14 and the outside of the spout stock 16.

Standard rotary-percussion drills usually have, extending therefrom, athreaded, male coupling through which rotation, percussion andpressurized fluid, for example air, are transmitted to the drill-pipe12. The spout stock 16 is provided, at its upper end, with an internallythreaded female coupling 58 for threadedly receiving the male couplingof a rotary-percussion drill. In order to transmit the pressurized fluidfrom the male coupling member of the rotary percussion drill to theannular space 32, the spout stock 16 is provided with passageway meanscommunicating the interior of the threaded female coupling 58 with theannular space 32. More particularly, the spout stock 16 is provided withsix passageways 60 extending from the interior of the threaded femalecoupling 58 to a portion 62 of the spout stock 16 which is intermediatethe coupling portion 51 and the downward-opening bore 52. Naturally,there can be more or less of the passageways 60, the only criterionbeing that the passageway means have sufiicient capacity to deliverpressurized fluid in the appropriate quantity.

The spout stock 16 is provided with an upward facing ledge 64 againstwhich a conventional spout shroud 65 is adapted loosely to seat. Thepurpose of the spout shroud 65 is to avoid material being ejected greatdistances through the lateral extensio 56. The spout shroud 65 directsall such material downwardly along the spout stock 16.

It will now be evident that the pressurized fluid, which is usually air,passes from the female coupling 58 through the passageways 60 and intothe annular space 32, from where it passes downwardly to the bit 18,through the passages 34, and into the opening 26. As the 'bit 18 chipsthe formation being traversed, the chips produced pass into the opening26, where they are picked up by the pressurized fluid emerging from thepassages 34 and are carried upwardly through the center of the interiortube 14, entrained in the fluid flow. They are then ejected through thelateral extension 56 of the bore 52, impinge against the spout shroud65, and drop downwardly outside the spout stock 16, there to be eitherdiscarded or collected for analysis.

By making the interior tube 14 completely independent of the drill-pipe12 as far as its axial and rotary motion is concerned, no part of thetorque or percussion stress is borne by the interior tube 14. Thispermits its manufacture as a comparatively weak tube whose only functionis to partition the downward flow of fluid from the upward flow offluid.

The drilling apparatus of this invention is of advantage in what isknown as tie-back operations, in which, after a vertical or oblique borehole has been drilled, a tie rod is passed downwardly through the centreof the interior tube 14 until its tip has reached through the bit 18 tothe bottom of the bore hole, whereupon the tie rod is grouted withcement while drill-pipe 12 is simultaneously withdrawn. The opening 26permits the withdrawal of the bit 18 over the tie rod.

While a preferred embodiment of this invention has been disclosedherein, those skilled in the art will appreciate that changes andmodifications may be made therein without departing from the spirit andscope of this invention as defined in the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In combination:

(a) a drill pipe having a bit end and a drive end;

(b) an interior tube positioned within said drill pipe to define anannular space between the drill pipe and the interior tube, saidinterior tube having a central passage therethrough;

(c) a spout stock secured to the drive end of said drill pipe andadapted to transmit impact and rotation to said drill pipe, said spoutstock having an internal downwardly-opening bore in which the interiortube is slidably received whereby the said bore is in communication withthe central passage of the interior tube, said spout stock includingmeans for connecting said spout stock to a source of pressurized fluidand a passage in said spout stock for directing said pressurized fluidinto the annular space between the drill pipe and the interior tube;and,

(d) a bit carried by said bit end, said bit having passage means forpassing fluid from said annular space into the interior tube and anannular portion against which the lower end of the interior tube isadapted to seat, said bit having a central opening extendingtherethrough and communicating with the central passage of the interiortube.

2. The combination claimed in claim 1, in which said spout stock isadapted to transmit impact and rotation to said drill-pipe from thethreaded male coupling mem ber of a rotary-percussion drill which alsodelivers pressurized fluid through said male coupling member, the spoutstock having a threaded female coupling at its upper end for receivingsaid male coupling member, the downward-opening bore having a lateralextension opening through the side of the spout stock, the spout stockhaving passageway means communicating the interior of said threadedfemale coupling with said annular space, whereby pressurized fluid canpass from said male coupling member into said annular space.

3. The combination claimed in claim 1, in which the drive end of thedrill-pipe is threadedly connected to the lower end of a cylindricalconnector pin of which the upper end is threadedly connected to saidspout stock coaxially with said downward-opening bore, said connectorpin being spaced from said interior tube, the spout stock having athreaded female coupling at its upper end for receiving the malecoupling member of a rotarypercussion drill which is adapted to deliverpressurized fluid through said male coupling member, the downwardopeningbore having a lateral extension opening through the side of the spoutstock, the spout stock having passageway means communicating theinterior of said threaded female coupling with the space between saidconnector pin and said interior tube, said connector pin beingconstructed to fail under excessive loads before the spout stock anddrill-pipe are damaged.

4. The combination claimed in claim 3, in which said means formaintaining further includes at least three axially aligned butcircumferentially distributed spacer elements secured to the outsidewall of said interior tube intermediate its ends.

5. The combination claimed in claim 4, in which said passageway meanscomprises a plurality of bore holes.

6. In combination: a drill-pipe having a bit end and a drive end, a bitcarried by said bit end, an interior tube positioned within saiddrill-pipe to define an annular space between the drill-pipe and theinterior tube, said bit having passage means by which fluid can passfrom said annular space into the interior tube, and a spout stocksecured to the drive end of said drill-pipe, and adapted to transmitimpact and rotation to said drill-pipe from the threaded male couplingmember of a rotary-percussion drill which also delivers pressurizedfluid through said male coupling member, the spout stock having athreaded female coupling at its upper end for receiving said malecoupling member and having an internal passage communicating the centreof said interior tube with the exterior of the spout stock, the spoutstock further having passageway means communicating the interior of saidthreaded female coupling with said annular space, whereby pressurizedfluid can pass from said male coupling member into said annular space.7. The combination claimed in claim 6, in which said passageway meanscomprises a plurality of bore holes.

References Cited UNITED STATES PATENTS 2,657,016 10/1953 Grable -2153,155,179 11/1964 Hunt 175215 3,198,256 8/1965 Kirby 166-99 3,370,6582/1968 Jansson 175215 NILE C. BYERS, 111., Primary Examiner

